SURFACE-MOUNTING OF POWER DEVICES TO ALUMINUM HEAT SINKS

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1 TO ALUMINUM HEAT SINKS SMTA PanPacific Thermal Management Hawaii March 11, 2004 Jim Fraivillig Fraivillig Technologies Boston, MA

2 PowerSite technology. Convert aluminum heat sinks to surface-mount applications => solder-on power devices Heat-seal copper to aluminum with all-polyimide TPI bond film insulation Excellent thermal management Improved performance with lower cost Patented

3 Heat-seal lamination POWERSITE TM COPPER POLYIMIDE ADHESIVE (thermoplastic, 0.15 mil) TPI FILM HEAT SINK (Aluminum) Performance advantages of PowerSites: Thin, highly thermally-conductive insulation All-polyimide durability Any heat sink No device attachment hardware

4 TPI bond film All-polyimide Heat-seals at o C to aluminum 200C operation OK 300C exposure OK

5 Next-Generation Thermal Management THERMAL INTERFACE Mica/grease Sil-Pads Ceramic (DBC) Insulated metal substrate (IMS) Introduction 1940s 1960s 1960s 1980s PowerSites 2000

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7 Typical PowerSite TM design conversion Conventional Method with Thermal Pads, Screws, Nuts, Clamps PowerSite Assembly

8 FT s TPI-based technologies ALL-POLYIMIDE TPI BOND FILM Sold as stand-alone insulation in punched parts Kapton MT + thin coating of thermoplastic polyimide adhesive (0.15 mil each side) Used as basis of other FT products POWERVIA THERMAL COLUMNS Mounting discrete power devices on PCB, providing thermal path to heat sink Present market standard: Plated-thru holes + Sil-Pad Patented POWERSITE SOLDERABLE PADS Mounting discrete power devices to heat sinks Present market standard: Sil-Pads with attachment hardware Patented POWERFLEX PRINTED CIRCUITS Power circuit pattern bonded to aluminum heat sink Present market standard: IMS ( Thermal Clad ) Patents pending

9 PowerFlex TM applications TPI printed circuits, bonded to... Aluminum baseplates

10 PowerFlex TM flexible interconnects DESIGN OPTIONS: Layer interconnection (to control board) Reduce footprint ( brick size) Increase power density Bond to any heat sink TPI bond film (on PCB bottom-side) Conventional PCB (FR4 epoxy glass) Stamped heat sinks

11 PowerVia technology Optimal through-hole hole thermal transfer

12 PowerVia technology Optimal through-hole hole thermal transfer PowerVias for D2Paks PowerVias inserted into PCB

13 Comparison of PowerVia with conventional thermal via

14 PowerSite thermal comparisons Versus insulator pads Laminated copper = PowerSite technology Versus IMS SOURCE: Parker Chomerics Technical study, 2000

15 PowerSite thermal comparisons Versus insulator pads Laminated copper = PowerSite technology PowerSite TM advantage: TO o C/W TO o C/W (compared to alumina-filled pad material) Versus IMS SOURCE: Parker Chomerics Technical study, 2000 PowerSite TM pads are equivalent to IMS (alumina-filled IMS material)

16 PowerFlex TM thermal transfer performance COMPARISON: TPI single-layer IMS single-layer Tested with Anatech pulse

17 PowerVia thermal transfer testing Thermal resistance testing of D2Pak (R j-s ), using Anatech pulse tester: PowerVias Conventional thermal via (plated-thru-hole + insulation pad + attachment hardware) D2Pak Cylindrical column PowerVia Rectangular column PowerVia Thermal vias

18 NOTE: Thermal resistance is junction-to-sink. Anatech measurement taken at steady-state. PCB secured to heat sink on PCB edges only ( psi?). Thermal via + pad thermal resistance is about 7 o C thru the power device+pcb and 4 o C/W thru the insulation pad.

19 Pressure dependency not a factor with PowerVias Conventional thermal vias require insulation pads insulations pads require high-pressure to optimize thermal transfer to the heat sink. PowerVias use non-isolating thermal grease or phase-change material.these thermal compounds have little pressure dependency (and very high thermal transfer). Thermal Impedance (oc-in2/w) Thermal Impedance vs Pressure Pressure (psi) Insulated pad Phase-change Thermal grease Isolated Non-isolated

20 PowerSite TM thermal durability ALL-POLYIMIDE: 200 o C continuous 300 o C exposure No-lead solder, no problem NOTE: PowerFlex and PowerVias use same TPI bond film, and have same thermal durability.

21 PowerSite technical challenges. Technology inertia Heat-seal processing Compatible PCB materials, configurations Heat sink surface Heat sink size and shape Volume drives cost

22 PowerSite applications. Telcom power supplies Portable devices Automotive controls Multi-chip modules Thermally-demanding applications, where cost and reliability are critical

23 PowerSite worldwide supply. Fraivillig Technologies developed PowerSites, PowerFlex and PowerVias EIS Fabrico U.S. technology licensee Union Bridge Asian licensee